The action of beta-bungarotoxin on neuromuscular junctions will be studied by a combination of electrophysiological, biochemical and anatomical techniques. We know from our earlier studies that the toxin is acting as a phospholipase when it destroys synaptic transmission. Our current problem is to decide if the selective hydrolysis of nerve terminal phospholipids is due to substrate specificity, inability of the nerve terminal to re-synthesize phospholipids or due to a recognition site on the nerve terminal quite distinct from the subtrate. Two approaches to the identification of molecular components of the nerve terminal will be utilized. In the first we shall purify synaptic vesicles to homogeneity and characterize them. In the second, we shall use axonal transport of labeled proteins to the nerve terminals to identify nerve terminal specific proteins.